In simple words, proximity sensors are the devices that are used to detect the presence of an object in its surroundings without any physical contact with the object. The IR proximity sensors detect objects by using an electromagnetic field or electromagnetic radiation beam. The sensors detect the presence of an object when the electromagnetic radiation has reflected the sensor. The object which is detected by the proximity sensors is known as targets.
Proximity sensors are available in different sizes, shapes (Circular or rectangular). Different materials (plastic, metallic, etc) some proximity sensors are a combination of both plastic and metallic material. The proximity sensors have more reliability due to the absence of the mechanical parts and it does not have contact with the target object. The proximity sensors which are designed for very short range can be used as touch switches. The proximity sensors are most commonly used in manufacturing industries for counting, detection, positioning, etc. The proximity sensors have longer life as compared to the other sensors.
WORKING PRINCIPLE OF PROXIMITY SENSORS:
We will now see the working principle of an Inductive proximity sensor. The inductive proximity sensor circuit is used for detecting metal objects and the Inductive proximity sensor does not detect any objects other than metals. The diagram shows the circuit diagram of an inductive proximity sensor. Which contains a voltage regulator, trigger circuit, an oscillator, electric coil, and magnetic field.
The electric coil produces a magnetic field when the power supply is given. As the circuit contains an oscillator, an alternating magnetic field is produced by the coils. Whenever a metal object is bought in the influence of the magnetic field, an eddy current will be produced in the metal object and circulates within the metal object. This causes an increase in load and a decrease in the amplitude of the magnetic field. When the metal target is moved closer to the metal object causes an increase in eddy current on the metal object and hence load on the oscillator increases and field amplitude decreases.
Read More: INTERFACING PROXIMITY SENSOR WITH ARDUINO